This invention relates to apparatus effective to automatically periodically reverse the operating direction of a windshield wiper motor to drive said windshield wiper repeatedly back and forth through a predetermined wipe angle and automatically stop it after a stop command in a predetermined park position.
In a traditional dual wiper front windshield wiper system, a single motor runs continuously in one direction; and back and forth wiping action is obtained therefrom through appropriate mechanical linkages. Such systems have been adequate and appropriate since a mechanical linking system is required anyway to drive two separate wipers from a single motor. However, with the increase in popularity of a single rear window mounted wiper, a mechanical direction reversing linkage is no longer desirable. With such a wiper, it is desirable to mount the wiper directly on the shaft of the motor or motor output gear box and periodically reverse direction of the motor itself to obtain back and forth wiping action. Various motor reversing control circuits have been proposed and used in the prior art, almost all of which have involved a complex and expensive system of limit switches to define the wipe angle limits during normal operation and further cause the wiper to stop in a park position when commanded. These limit switches introduce undesirable mechanical complexity and expense and, for the most part, greatly complicate the process of changing the wipe angle from one vehicle or application to another.